2181707021 has 24 divisors (see below), whose sum is σ = 2482358400. Its totient is φ = 1912886976.

The previous prime is 2181706949. The next prime is 2181707051. The reversal of 2181707021 is 1207071812.

It is not a de Polignac number, because 2181707021 - 2¹⁰ = 2181705997 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181707051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 577280 + ... + 581046.

It is an arithmetic number, because the mean of its divisors is an integer number (103431600).

Almost surely, 2^2181707021 is an apocalyptic number.

It is an amenable number.

2181707021 is a deficient number, since it is larger than the sum of its proper divisors (300651379).

2181707021 is a wasteful number, since it uses less digits than its factorization.

2181707021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3965 (or 3952 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 29.

The square root of 2181707021 is about 46708.7467290656. The cubic root of 2181707021 is about 1296.9766073203.

Adding to 2181707021 its reverse (1207071812), we get a palindrome (3388778833).

The spelling of 2181707021 in words is "two billion, one hundred eighty-one million, seven hundred seven thousand, twenty-one".